1. Field of the Invention
The present invention relates to a stalk switch device that is provided near a steering wheel of an automobile and used for beam switching operation, turn signal operation, etc.
2. Description of the Related Art
Generally, a pair of stalk switch devices is disposed on both sides of a housing fixed to a steering column, etc., thereby constituting a combination switch. Each of the stalk switch devices is tiltably operated in a proper direction, so that beam switching of a headlamp, or switching operation of a turn signal, a wiper, etc., can be performed. For example, in the case of the stalk switch device that tiltably operates an operating lever substantially in a vertical direction to perform turn signal operation, the operating lever is tiltably operated substantially in a back-and-forth direction so that beam switching (low-beam or high-beam switching) operation or passing operation of a headlamp can be performed.
The general configuration of such a stalk switch device includes a base of the operating lever that is rotatably connected with the lever support, and the operating lever is tiltable in a predetermined operation plane with respect to the lever support. Further, the lever support is rotatably connected with a housing that is a stator member. The operating lever and the lever support are integrally tiltable in a separate operation plane orthogonal to the above operation plane. That is, the axis of rotation of the operating lever with respect to the lever support, and the axis of rotation of the operating lever and lever support with respect to the housing are substantially orthogonal to each other so that the operating lever can be tiltably operated in the two substantially orthogonal directions. A circuit board is fixed to the housing, and the circuit board extends substantially parallel to the separate operation plane. Also, a slider is disposed on the circuit board. Here, when the operating lever is tiltably operated, this slider is driven to move along the circuit board. Therefore, by the positional change of the slider, switching operation of a contact with respect to the circuit board can be performed (for example, refer to U.S. Pat. No. 5,861,594 (corresponding to JP-A-10-172389).
On the other hand, in the stalk switch device configured as described above, when the operating lever and the lever support are integrally tilted with respect to the housing (for example, at the time of turn signal operation), the operation plane of the operating lever is substantially parallel to the circuit board. Therefore, if a driving part that is provided in the lever support, etc. so as to protrude therefrom is made to engage a corresponding slider, this driving part moves along the circuit board at the time of operation. Therefore, it is relatively easy to secure a sufficient amount of movement for the slider. However, when the operating lever is tilted with respect to the lever support (for example, at the time of beam switching operation), the operation plane of the operating lever is substantially orthogonal to the circuit board, and the driving part that is provided in the operating lever so as to protrude therefrom cannot be moved along the circuit board at the time of operation. Thus, in order to have substantial movement of the slider, which is driven in engagement with the driving part, along the circuit board at the time of operation, a countermeasure becomes necessary, such as a large setting of the radius of rotation of the driving part. That is, when the operating lever is tiltably operated with respect to the lever support, the amount of movement of the slider that is engaged with the driving part considerably decreases as compared with the amount of movement of the driving part provided in the operating lever. Thus, in order to secure a sufficient amount of movement for the slider, an engagement part between the slider and the driven part should be largely separated from the rotation center of the operating lever. Such design constraint became a factor that the housing or lever support is hindered from being made small and thin. In addition, if the amount of movement of the slider needed for the switching operation of the contact is not sufficient, degradation of reliability degradation, or increase in cost will be inevitably entailed.